What are Medullary Rays in Oak wood?

What are Medullary Rays in Oak wood?

Oak furniture can often be partial to tiny white marks or specks that can curve and sometimes be mistaken for water damage or storage issues. However, these markings are a naturally occurring finish called ‘Medullary Rays’ and they can help to add charm, character, and overall beauty to any oak furniture piece. 

All trees have Medullary Rays in their wood as it is the basic biology of the tree. These rays are most pronounced in red oak and in white oak when these particular species are quartersawn the rays manifest themselves across the face of the wood in a variety of ways.

Medullary Rays are also known as pith rays, oak figures, or tiger stripes but they all refer to the same specks within the timber. 

They are horizontal rays that extend away from the core of a tree towards the bark. Usually, they appear to be very shiny and vary in height and length.

What causes Medullary Rays?

Medullary Rays are caused by plant cells that stretch away from the tree’s cells or growth rings. These ribbon-like cells carry the sap through the trunk which makes them an essential part of the growing process. When the trunk is cut the cells produce silvery marks across the sawn area and they become more prominent once the oak has been polished, varnished, or oiled.

Medullary Rays are often mistaken for damage or a flaw in the wood but they actually indicate that the furniture item has been made from the finest and most expensive quarter-sawn wood.

In logging and carpentry terms, oak trees can be sawn in two different ways:

  • Plain Sawing (Tangenial Sawing) - is a process that gains the most timber from a tree trunk, it is the fastest form of timber production and it provides far less waste making it a popular harvesting method.
  • Quarter Sawing - is a slower process and produces less timber and is often much more expensive to produce.

Due to the direction of ring growth in a tree, quarter-sawn timber is far greater in strength and also shows the most medullary rays on its surface.

Are there any other types of timber markings?

There may be some other markings on your furniture that are also naturally occurring elements of the timber that was used to make the piece.

Like all organic materials, timber has lots of natural characteristics, and because it responds to environmental elements over time these markings are what add to the personality of the wood.

Cracks or splits in timber are called Shakes. These are usually filled but in some cases may be partly filled to maintain the wood. Shakes are naturally occurring marks in the wood, usually between or through the growth rings of the tree. These may take place as a result of external stressors such as frost or high winds. Due to the strength of the oak, they are never a cause for concern.

Checks are the formation of cracks in the wood often caused by tension that develops in the outer parts of a tree when an improper drying process is used. Surface checking usually does not extend from one side to the other side of a piece of wood and is not a cause for concern. Oak can have surface checks everywhere, which many people feel adds character to the wood and make the furniture piece unique and different from other pieces.

Knots are circular or oval-shaped markings caused by natural forces. They can vary widely in size and can occur under two circumstances:

  • When a new branch grows from the trunk a conjunction forms a dark spot called a ‘live knot.’
  • Due to tree scaring that manifests as ‘dead knots’ on wood.

Every knot, medullary ray, and crack is a testament to the many years a tree has lived through. This is what makes real wood more interesting and special than other materials.

Just like naturally occurring knots, medullary rays should be enjoyed as part of the oak furniture's appeal and charm.

Are Medullary Rays a sign of good quality?

In short, yes, medullary rays are a sign that your furniture is made from the finest organic materials. Because we only select the finest oak for our collections you may find some medullary rays in the timber we use. Here at House of Oak, we encourage customers to take pride in and embrace the naturally occurring markings in the wooden pieces they choose to place within their home and see them not only as a sign of unique beauty and characterful charm but also as an indication of sophistication, quality, and finery.

So, next time you take a glance at your oak dining table or gaze over at your sideboard just remember that those silver sparks of light along its surface are an indication of the time-consuming labour and love that goes into its craftsmanship.